This invention relates to a compressor system for a reciprocating machine and more particularly to an improved positive displacement crankcase compression device for such a machine.
En many types of reciprocating machines, such as internal combustion engines, it has been proposed to employ the variable volume of the crankcase chamber as the piston reciprocates as a device for supercharging or pressuring the intake charge. When this concept is applied to four cycle engines, it is possible to obtain two supercharging strokes for each firing of the engine.
However, even though the crankcase is used as a compressing device, the actual increase in output of the engine has been only slight. The reason for this is because of the large volume of the crankcase chamber which does not act to provide any compression and also the drop of charging efficiency caused by the heating of the compressed mixture by the engine. In order to increase the supercharging effect, it is necessary to reduce the dead volume in the crankcase chamber. This is done to increase the compression ratio which compression ratio is obtained by dividing the sum of the crankcase volume V.sub.c when the piston is at its bottom dead center position and the stroke V.sub.h caused by the change in volume when the piston moves to its top dead center position. This is similar to the manner in determining the compression ratio of the engine on the piston side. Since a large percentage of the volume of the crankcase is occupied between the webs of the crankshaft, it is difficult to reduce the crankcase volume V.sub.c.
It has been proposed to provide a positive type displacement arrangement in the crankcase chamber so as to operate like a rotary type vacuum pump. When this has been done, however, a rotor has been slideably supported within the crankcase chamber and is driven by the crankshaft so as to act as a pump. However, this provides quite a complicated structure.
It is, therefore, a principal object to this invention to provide an improved positive displacement, crankcase compression system for a reciprocating machine that employs only the crankshaft and connecting rod as the compressor elements.
It is a further object to this invention to provide an improved crankcase compressor for a reciprocating machine.
In addition to the difficulties as aforenoted, it has also been the practice to employ reed type check valves both in the admission system for the air to the crankcase chamber that will be compressed and also on the discharge side of the crankcase compressor. The use of such reed type valves gives a flow resistance to the charge which decreases the pumping efficiency and also does not permit control of the timing when the respective ports are opened and closed.
It is, therefore, a still further object to this invention to provide an improved valving arrangement for a compressor of this type.
It is a further object to this invention to provide a valving arrangement for a compressor within the crankcase of a reciprocating machine that employs the actual components of the machine as the valving elements.